The name of the famous adventurer seemed to make the best of impressions upon Mr. Kesselbach. Lupin did not fail to observe the fact and exclaimed:

"Aha, my dear sir, you breathe again! Arsene Lupin is a delicate, squeamish burglar. He loathes bloodshed, he has never committed a more serious crime than that of annexing other people's property ... a mere peccadillo, eh? And what you're saying to yourself is that he is not going to burden his conscience with a useless murder. Quite so... .

But will your destruction be so useless as all that? Everything depends on the answer. And I assure you that I'm not larking at present. Come on, old chap!"

He drew up his chair beside the arm-chair, removed the prisoner's gag and, speaking very plainly:

"Mr. Kesselbach," he said, "on the day when you arrived in Paris you entered into relations with one Barbareux, the manager of a confidential inquiry agency; and, as you were acting without the knowledge of your secretary, Chapman, it was arranged that the said Barbareux, when communicating with you by letter or telephone, should call himself 'the Colonel.' I hasten to tell you that Barbareux is a perfectly honest man.

But I have the good fortune to number one of his clerks among my own particular friends. That is how I discovered the motive of your application to Barbareux and how I came to interest myself in you and to make a search or two here, with the assistance of a set of false keys ... in the course of which search or two, I may as well tell you, I did not find what I was looking for."

He lowered his voice and, with his eyes fixed on the eyes of his prisoner, watching his expression, searching his secret thoughts, he uttered these words:

"Mr. Kesselbach, your instructions to Barbareux were that he should find a man hidden somewhere in the slums of Paris who bears or used to bear the name of Pierre Leduc. The man answers to this brief description: height, five feet nine inches; hair and complexion, fair; wears a moustache. Special mark: the tip of the little finger of the left hand is missing, as the result of a cut. Also, he has an almost imperceptible scar on the right cheek. You seem to attach enormous importance to this man's discovery, as though it might lead to some great advantage to yourself. Who is the man?"

"I don't know."

The answer was positive, absolute. Did he know or did he not know? It made little difference. The great thing was that he was determined not to speak.

"Very well," said his adversary, "but you have fuller particulars about him than those with which you furnished Barbareux."

"I have not."

"You lie, Mr. Kesselbach. Twice, in Barbareux's presence, you consulted papers contained in the morocco case."

"I did."

"And the case?"

"Burnt."

Lupin quivered with rage. The thought of torture and of the facilities which it used to offer was evidently passing through his mind again.

"Burnt? But the box? ... Come, own up ... confess that the box is at the Credit Lyonnais."

"Yes."

"And what's inside it?"

"The finest two hundred diamonds in my private collection."

This statement did not seem to displease the adventurer.

"Aha, the finest two hundred diamonds! But, I say, that's a fortune!

... Yes, that makes you smile... . It's a trifle to you, no doubt.

... And your secret is worth more than that... . To you, yes ...

but to me? ..."

He took a cigar, lit a match, which he allowed to go out again mechanically, and sat for some time thinking, motionless.

The minutes passed.

He began to laugh:

"I dare say you're hoping that the expedition will come to nothing and that they won't open the safe? ... Very likely, old chap! But, in that case, you'll have to pay me for my trouble. I did not come here to see what sort of figure you cut in an arm-chair... . The diamonds, since diamonds there appear to be ... or else the morocco case... .

There's your dilemma." He looked at his watch. "Half an hour... . Hang it all! ... Fate is moving very slowly... . But there's nothing for you to grin at, Mr. Kesselbach. I shall not go back empty-handed, make no mistake about that! ... At last!"

It was the telephone-bell. Lupin snatched at the receiver and, changing the sound of his voice, imitated the rough accent of his prisoner:

"Yes, Rudolf Kesselbach ... you're speaking to him... . Yes, please, mademoiselle, put me on... . Is that you, Marco? ... Good... . Did it go off all right? ... Excellent! ... No hitch? ... My best compliments! ... Well, what did you pick up? ... The ebony box?

... Nothing else? ... No papers? ... Tut, tut! ... And what's in the box? ... Are they fine diamonds? ... Capital, capital! ... One minute, Marco, while I think... . You see, all this... . If I were to tell you my opinion... . Wait, don't go away ... hold the line.

He turned round.

"Mr. Kesselbach, are you keen on your diamonds?"

"Yes."

"Would you buy them back of me?"

"Possibly."

"For how much? Five hundred thousand francs?"

"Five hundred thousand ... yes."

"Only, here's the rub: how are we to make the exchange? A cheque? No, you'd swindle me ... or else I'd swindle you... . Listen. On the day after to-morrow, go to the Credit Lyonnais in the morning, draw out your five hundred bank-notes of a thousand each and go for a walk in the Bois, on the Auteuil side... . I shall have the diamonds in a bag: that's handier... . The box shows too much... ."

Kesselbach gave a start:

"No, no ... the box, too... . I want everything... ."

"Ah," cried Lupin, shouting with laughter, "you've fallen into the trap!

... The diamonds you don't care about ... they can be replaced.

... But you cling to that box as you cling to your skin... . Very well, you shall have your box ... on the word of Arsene ... you shall have it to-morrow morning, by parcel post!"

He went back to the telephone:

"Marco, have you the box in front of you? ... Is there anything particular about it? ... Ebony inlaid with ivory... . Yes, I know the sort of thing... . Japanese, from the Faubourg Saint-Antoine.

... No mark? ... Ah, a little round label, with a blue border and a number! ... Yes, a shop-mark ... no importance. And is the bottom of the box thick? ... Not very thick... . Bother! No false bottom, then? ... Look here, Marco: just examine the ivory inlay on the outside ... or, rather, no, the lid." He reveled with delight. "The lid! That's it, Marco! Kesselbach blinked his eyes just now... . We're burning! ... Ah, Kesselbach, old chap, didn't you see me squinting at you? You silly fellow!" And, to Marco, "Well, what do you see? ... A looking-glass inside the lid? ... Does it slide? ... Is it on hinges? ... No! ... Well, then, break it... . Yes, yes, I tell you to break it... . That glass serves no purpose there ... it's been added since!" He lost patience. "Mind your own business, idiot! ... Do as I say! ..."

He must have heard the noise which Marco made at the other end of the wire in breaking the glass, for he shouted, in triumph.

"Didn't I tell you, Mr. Kesselbach, that we should find something? ...

Hullo! Have you done it? ... Well? ... A letter? Victory! All the diamonds in the Cape and old man Kesselbach's secret into the bargain!"

He took down the second receiver, carefully put the two discs to his ears and continued: